Blender Texture working differently when Imported to Unity
Could it be that the normals of mirrored side of the dragon are facing the wrong way?  

If you enable Backface Culling  you will see your model as it will appear in Unity. 

If you notice a difference in your mesh when Backface Culling is enabled then you probably do have inverted normals.

To fix this, in Edit mode, with all of the dragon selected open the Tools panel and then the Shading/UV tab > Normals > Recalculate Normals.